From: Michael Fuhr <mike@fuhr.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Sebastian Siewior <lavish@kamp-dsl.de>
Cc: pgsql-sql@postgresql.org
Subject: Re: Problem with a Pettern Matching Check
Date: Mon, 15 Aug 2005 18:43:49 -0600
Message-ID: <20050816004349.GA71850@winnie.fuhr.org> (raw)
In-Reply-To: <18684.1124151683@sss.pgh.pa.us>
References: <20050816001950.2225e5b8@mikejones.ghb.fh-furtwangen.de>
<20050815224208.GA51332@winnie.fuhr.org>
<18684.1124151683@sss.pgh.pa.us>
On Mon, Aug 15, 2005 at 08:21:23PM -0400, Tom Lane wrote:
> Michael Fuhr <mike@fuhr.org> writes:
> > The CHAR(3) specification causes the value to be space-padded, so
> > '1' becomes '1 ' (the digit "one" followed by two spaces).
>
> Actually, we seem to be going out of our way to make this case fail.
> Given that we consider trailing spaces in char(n) to be semantically
> insignificant, would it make sense to strip them before doing the
> regex pattern match?
How standards-compliant would that be? Does the standard specify
what should happen when using SIMILAR TO with a char(n) value?
I notice that equality and SQL regular expressions treat trailing
spaces differently -- is that intentional or accidental?
CREATE TABLE foo (test char(3));
INSERT INTO foo VALUES ('1');
SELECT test, test = '1', test SIMILAR TO '1' FROM foo;
test | ?column? | ?column?
------+----------+----------
1 | t | f
(1 row)
SELECT test, test = '1 ', test SIMILAR TO '1 ' FROM foo;
test | ?column? | ?column?
------+----------+----------
1 | t | t
(1 row)
> That would happen automatically if we allowed
> the char(n) value to promote to text --- and the only reason it's
> not doing so is that there's an extra ~ operator definition that
> specifically prevents that (bpcharregexeq).
"bpcharregexeq" -- didn't Philip Glass write the score to that?
--
Michael Fuhr
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To: pgsql-sql@postgresql.org
Cc: mike@fuhr.org, tgl@sss.pgh.pa.us, lavish@kamp-dsl.de
Subject: Re: Problem with a Pettern Matching Check
In-Reply-To: <20050816004349.GA71850@winnie.fuhr.org>
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